Hybrid Portal axles.

rusty_tlc

New member
Hybrids sound cool, a mostly stock axle with the portal box at the end. Right now I think most Co.'s that do this use mog or volvo parts but I've read at least one thread over on Pirates (Ih8mud?) about people trying to engineer their own production units that bolt up to a dana axle. So it looks like the cost will go down and they will be showing up on the trails a lot more.

What are the advantages/disadvantages to portal axles?
 

Dirty Harry

Moderator
Staff member
There is a place called TKO Jeeps out of Texas that was working on a bolt on portal box. I actually saw them on a Jeep at the Off-Road Impact Show last January, but I have not heard much about it since then. I was not very impressed with the product, it just looked really rough to me and the geometry did not look right.

In general I think that portals are great because you can get them for relatively cheap with cable actuated lockers, really low gears, and a ton of ground clearance. They are heavy, but that can be an advantage or disadvantage depending on the situation. The costs start adding up when you look at adding pinion conversions and disc brakes. Uptravel is going to be an issue unless you design the frame around the axles, and even then you have things like the oil pan to deal with. As you mentioned though, this is not such a big deal when you have so much ground clearance. There have been people breaking the cast reduction box housing in competition use, but overall they are very strong.

I think that your biggest challenge is going to be designing a suspension around the portal axles. In addition to the mounting constraints, the reduction boxes act like foot tall lift blocks and leaf springs will not be adequate in the front or back. This may not be a big issue for you though if you are already planning a three or four link suspension.

More Mog portal info can be found at http://www.exaxt.ca/ and http://www.killeraxles.com/
 

Dirty Harry

Moderator
Staff member
I have seen guys use Hummer outers for hybrid portal setups too. I think that the only real advantage to using a stock center section is that you will have a wider selection of gear ratios, that is why most guys doing this have used 9" diffs. You have to flip the diff too because the portal outers change the rotation of the drivetrain unless you use 3 gear planetaries (not found on Mogs or Volvos).
 

Sauce

Active member
rusty_tlc said:
Nolans Sunray thread

The shot with a 5 gal bucket and a coke can under the diff really show off just how much clerance these guys have.
oh my goodness, I just made a mess all over my keyboard at work, how embarassing! That thing is bad a$$ and it only weighs 180 lbs to boot! The only question I have is how big are those tires, i read the thread and couldn't find the size.
 

Dirty Harry

Moderator
Staff member
Yeah that is about the coolest axle EVER. He said that it ended up weighing 280 pounds (that is about $10 per pound) with the brake hardware and full of fluid, still pretty good considering what you get. The tires are 40" MT/Rs and he has 11.5" ground clearance with them.
 

rusty_tlc

New member
I drove by the Mercedes dealer ship today. Wonder what they would say if I asked to test drive a Unimog?
Probably get a blank stare. :disagree:
 

spoon

New member
Dirty Harry said:
Yeah that is about the coolest axle EVER. He said that it ended up weighing 280 pounds (that is about $10 per pound) with the brake hardware and full of fluid, still pretty good considering what you get. The tires are 40" MT/Rs and he has 11.5" ground clearance with them.
11.5" clearance on 40" MT/Rs? Must be a typo. I got 11.75" clearance with 40" MT/Rs @ 10 psi with a slightly shaved fo-teen bolt. Measured a 5-gallon bucket and a can and came up with a measurement of 19.75". Gotta love the clearance that a portal gives, but I still can't get excited about using 1960's european military surplus parts on my rig. From what I have heard, it doesn't seem that the portal gearboxes can stand up to abusive applications for a long period of time.
 

rusty_tlc

New member
spoon said:
11.5" clearance on 40" MT/Rs? Must be a typo. I got 11.75" clearance with 40" MT/Rs @ 10 psi with a slightly shaved fo-teen bolt. Measured a 5-gallon bucket and a can and came up with a measurement of 19.75". Gotta love the clearance that a portal gives, but I still can't get excited about using 1960's european military surplus parts on my rig. From what I have heard, it doesn't seem that the portal gearboxes can stand up to abusive applications for a long period of time.
They still make UNIMOG's, spares are available in the US. U-joints and birfields can't stand up to abusive applications for a long period of time either.

When I was in Europe I watched some kind MOG of competition on TV. It was like a combination of mud bogging, rock crawling and hill climb.
 
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